parser: new array init syntax

vlib/builtin/array_test.v

@@ -724,6 +724,7 @@ fn test_left_shift_precendence() {
 }
 
 fn test_array_with_cap() {
-	a := []int{cap:10, len:1 }
-	//assert a.len == 1
+	a4 := []int{cap:10, len:1 }
+	assert a4.len == 1
+	assert a4.cap == 10
 }

vlib/v/ast/ast.v

@@ -635,6 +635,10 @@ pub:
 	is_fixed  bool
 	has_val   bool
 	mod       string
+	len_expr  Expr
+	has_len   bool
+	has_cap   bool
+	cap_expr  Expr
 mut:
 	elem_type table.Type
 	typ       table.Type

vlib/v/gen/cgen.v

@@ -963,33 +963,7 @@ fn (mut g Gen) expr(node ast.Expr) {
 	// println('cgen expr() line_nr=$node.pos.line_nr')
 	match node {
 		ast.ArrayInit {
-			type_sym := g.table.get_type_symbol(it.typ)
-			if type_sym.kind != .array_fixed {
-				// elem_sym := g.table.get_type_symbol(it.elem_type)
-				elem_type_str := g.typ(it.elem_type)
-				if it.exprs.len == 0 {
-					// use __new_array to fix conflicts when the name of the variable is new_array
-					g.write('__new_array($it.exprs.len, $it.exprs.len, sizeof($elem_type_str))')
-				} else {
-					len := it.exprs.len
-					g.write('new_array_from_c_array($len, $len, sizeof($elem_type_str), ')
-					g.write('($elem_type_str[$len]){\n\t\t')
-					for expr in it.exprs {
-						g.expr(expr)
-						g.write(', ')
-					}
-					g.write('\n})')
-				}
-			} else {
-				g.write('{')
-				for i, expr in it.exprs {
-					g.expr(expr)
-					if i != it.exprs.len - 1 {
-						g.write(', ')
-					}
-				}
-				g.write('}')
-			}
+			g.array_init(it)
 		}
 		ast.AsCast {
 			g.as_cast(it)
@@ -3346,3 +3320,45 @@ ${interface_name} I_${cctype}_to_${interface_name}(${cctype} x) {
 	}
 	return sb.str()
 }
+
+fn (mut g Gen) array_init(it ast.ArrayInit) {
+	type_sym := g.table.get_type_symbol(it.typ)
+	if type_sym.kind != .array_fixed {
+		// elem_sym := g.table.get_type_symbol(it.elem_type)
+		elem_type_str := g.typ(it.elem_type)
+		if it.exprs.len == 0 {
+			g.write('__new_array(')
+			if it.has_len {
+				g.expr(it.len_expr)
+				g.write(', ')
+			} else {
+				g.write('0, ')
+			}
+			if it.has_cap {
+				g.expr(it.cap_expr)
+				g.write(', ')
+			} else {
+				g.write('0, ')
+			}
+			g.write('sizeof($elem_type_str))')
+		} else {
+			len := it.exprs.len
+			g.write('new_array_from_c_array($len, $len, sizeof($elem_type_str), ')
+			g.write('($elem_type_str[$len]){\n\t\t')
+			for expr in it.exprs {
+				g.expr(expr)
+				g.write(', ')
+			}
+			g.write('\n})')
+		}
+	} else {
+		g.write('{')
+		for i, expr in it.exprs {
+			g.expr(expr)
+			if i != it.exprs.len - 1 {
+				g.write(', ')
+			}
+		}
+		g.write('}')
+	}
+}

vlib/v/parser/containers.v

@@ -70,16 +70,32 @@ fn (mut p Parser) array_init() ast.ArrayInit {
 	if exprs.len == 0 && p.tok.kind != .lcbr && has_type {
 		p.warn_with_pos('use `x := []Type{}` instead of `x := []Type`', last_pos)
 	}
+	mut has_len := false
+	mut has_cap := false
+	mut len_expr := ast.Expr{}
+	mut cap_expr := ast.Expr{}
 	if p.tok.kind == .lcbr && exprs.len == 0 {
 		// `[]int{ len: 10, cap: 100}` syntax
 		p.next()
 		for p.tok.kind != .rcbr {
 			key := p.check_name()
 			p.check(.colon)
-			if key !in ['len', 'cap', 'init'] {
-				p.error('wrong field `$key`, expecting `len`, `cap`, or `init`')
+			match key {
+				'len' {
+					has_len = true
+					len_expr = p.expr(0)
+				}
+				'cap' {
+					has_cap = true
+					cap_expr = p.expr(0)
+				}
+				'default' {
+					p.expr(0)
+				}
+				else {
+					p.error('wrong field `$key`, expecting `len`, `cap`, or `default`')
+				}
 			}
-			p.expr(0)
 			if p.tok.kind != .rcbr {
 				p.check(.comma)
 			}
@@ -99,6 +115,10 @@ fn (mut p Parser) array_init() ast.ArrayInit {
 		typ: array_type
 		exprs: exprs
 		pos: pos
+		has_len: has_len
+		len_expr: len_expr
+		has_cap: has_cap
+		cap_expr: cap_expr
 	}
 }